There is topic about sky and cubemaps: [VIDEO TUTORIAL] Creating High Resolution Space Scapes - Community Content, Tools and Tutorials - Unreal Engine Forums
Yes it is about stars, nebulas etc. sky, but if you have cloudy texture that can be turned into cubemap then watch tutorial in above link.
Few thigs that work for ue4 (and are not cleared in video):
- use Ogre setting to export those star textures
- AMD tools after you exported in ogre format are best for making cubemap, else you need photoshop for rotating some face textures
And
If you have crappy and very low level resolution on your sky, it is due to distance to sky dome and fact that mip map optimization kicks in.
So change your compression (or LOD) setting in that dropdown menu in properites of cubemap texture. I think one you want is “no mipmap”
PS. same cubemap trick with mapping it to sphere uv (but reversed) works wonders for planets, it almost eliminates ugly polar regions stretching.